1. Field of the Invention
The present invention relates to a component edge detecting method, a component edge detecting program and a component inspection apparatus, and, in particular, to a component edge detecting method applicable to an appearance inspection for an electronic component mounted on a printed circuit substrate, a component edge detecting program for causing a computer to execute the method, and a component inspection apparatus carrying out this method.
2. Description of the Related Art
Inspection of respective electronic components mounted on a printed circuit substrate carried out before shipping of the circuit substrate which will be used in an electronic apparatus or such, includes a verification as to whether or not predetermined electronic components are positively mounted, whether or not the mounted positions thereof are proper, whether or not soldering connections between electrodes of the electronic components and electrically conductive patterns provided on the printed circuit substrate are proper, or such. Upon carrying out these verification operations, for reasons that these particular electronic components are very small (on the order of point millimeters, for example), it is necessary to carry out the verification operations on many of these products within a limited duration, or such, it may be difficult or it may be not suitable to carry out these inspection operations visually with naked eyes directly. Therefore, a method is demanded for taking a photograph of the to-be-inspected printed circuit substrate and analyzing the thus-obtained image through analytic processing with the use of a computer program so as to carry out these inspection operations efficiently.
FIG. 1 shows a magnified view of one example of such a to-be-inspected printed circuit substrate. Further, FIG. 2 illustrates a part of FIG. 1 in an easily understandable manner. As shown, an electronic component including a component body and electrodes are mounted on the printed circuit substrate on which electrically conductive patterns (indicated in the figures as PATTERN) are previously printed. As a result of the electrodes and the electrically conductive patterns being soldered (indicated in the figures as SOLDER) together, both are electrically connected together, and also, the electronic component having the electrodes are fixedly mounted on the printed circuit substrate.
For example, Japanese Laid-open Patent Application No. 2003-110298 discloses a technology concerning a mounted component inspection apparatus for carrying out inspection for verifying as to whether there is a positional error of electronic components mounted on a printed circuit substrate. According to the technology, for an electronic component having a body part and an electrode part, comparison processing is carried out on an image of the substrate on which the electronic component is mounted, with the use of a matching plate extracted from the image, in particular, from an edge part of the electrode part except a boundary line between the body part and the electrode part. Thereby, inspection for verifying as to whether components are actually mounted, whether there is no erroneous mounting, and whether the components are mounted in a proper manner is carried out.
Japanese Laid-open Patent Application No. 63-229577 discloses a technology in which, upon obtaining edge information of objects for the purpose of obtaining shape information of the objects having cross-sectional shapes configuring a latex grain aggregate, a fiber aggregate or such, noise information present in a background of the objects is positively removed so as to improve the preciseness and the processing speed of the edge detection processing.
Japanese Laid-open Patent Application No. 2003-246165 discloses a technology relating to appearance inspection for a mirror surface member or such directed to the improvement in the accuracy and the speed of component edge detection processing even when much noise is included, upon extracting an inspection target from an area of an image including a to-be-inspected object.